1. Field of the Invention
The present invention relates to an internal combustion engine system and a starting method of an internal combustion engine. More specifically the invention pertains to an internal combustion engine system including an internal combustion engine equipped with in-cylinder fuel injection valves for in-cylinder injection of a fuel, as well as to a starting method of the internal combustion engine in the internal combustion engine system.
2. Description of the Prior Art
A proposed internal combustion engine system includes an internal combustion engine equipped with in-cylinder fuel injection valves for direct in-cylinder injection of a fuel and intake port fuel injection valves for injection of the fuel in an intake port (see, for example, Japanese Patent Laid-Open Gazette No. H11-270385). At a start of the internal combustion engine, this prior art system prohibits fuel injection from the in-cylinder fuel injection valves until a rise of the pressure of the fuel supplied to the in-cylinder fuel injection valves (fuel pressure) to a preset reference level. The internal combustion engine starts with the fuel injected from the intake port fuel injection valves. This accelerates microparticulation of the fuel in the cylinders to improve the starting performance of the internal combustion engine and prevent the deterioration of emission. This prior art system stops fuel injection from the intake port fuel injection valves in response to the rise of the fuel pressure to the preset reference level and starts fuel injection from the in-cylinder fuel injection valves.